Oh, he is a stinker!!
Today he had a good long morning nap, and then off we went to our local craft market and then the park for a picnic. Daddy took him for a walk at nap time, no joy. Car ride, ditto. Attempted to feed to sleep when we got home, and he just got really cross. So I gave up and got him up for a bit. He finally crashed at 4pm, 2.5hrs after his normal nap time! And of course he's fought bedtime as well, even though he looks exhausted.
I surmise from this that he will only sleep if it's boring. Honestly!!